diff --git a/src/Updux.ts b/src/Updux.ts
index b3c8952..fd3ac49 100644
--- a/src/Updux.ts
+++ b/src/Updux.ts
@@ -22,6 +22,7 @@ import { buildInitial, AggregateState } from './initial.js';
 import { buildReducer, MutationCase } from './reducer.js';
 import { augmentGetState, augmentMiddlewareApi, buildEffectsMiddleware, EffectMiddleware } from './effects.js';
 import { ToolkitStore } from '@reduxjs/toolkit/dist/configureStore.js';
+import prepare from 'immer';
 
 type MyActionCreator = { type: string } & ((...args: any) => any);
 
@@ -132,7 +133,9 @@ export default class Updux<
             Object.entries(this.#subduxes)
                 .filter(([slice, { selectors }]) => selectors)
                 .map(([slice, { selectors }]) =>
-                    R.mapValues(selectors, (s) => (state) => s(state[slice])),
+                    R.mapValues(selectors, (s) => (state = {}) => {
+                        return s(state?.[slice])
+                    }),
                 ),
         );
 
@@ -218,6 +221,7 @@ export default class Updux<
         }
 
         (store as any).actions = this.actions;
+        (store as any).selectors = this.selectors;
 
 
         return store as ToolkitStore<
@@ -276,10 +280,12 @@ export default class Updux<
             matcher = matcher.match;
         }
 
+        const immerMutation = (...args) => prepare(mutation(...args));
+
         this.#localMutations.push({
             terminal,
             matcher,
-            mutation,
+            mutation: immerMutation,
         });
     }
 
diff --git a/src/buildActions.ts b/src/buildActions.ts
index bee0ebb..f93ac42 100644
--- a/src/buildActions.ts
+++ b/src/buildActions.ts
@@ -21,7 +21,7 @@ export function buildActions(localActions, subduxes) {
         if (!subdux) continue;
 
         for (const a in subdux) {
-            if (actions[a]) {
+            if (actions[a] && subduxes[actions[a]].actions[a] !== subdux[a]) {
                 throw new Error(
                     `action '${a}' defined both in subduxes '${actions[a]}' and '${slice}'`,
                 );
diff --git a/src/reducer.ts b/src/reducer.ts
index c11c60b..1f7b956 100644
--- a/src/reducer.ts
+++ b/src/reducer.ts
@@ -4,6 +4,7 @@ import * as R from 'remeda';
 import { Dux } from './types.js';
 import { Mutation } from './Updux.js';
 import u from '@yanick/updeep-remeda';
+import prepare from 'immer';
 
 export type MutationCase = {
     matcher: (action: Action) => boolean;
@@ -35,9 +36,10 @@ export function buildReducer(
             .forEach(({ mutation, terminal: t }) => {
                 if (t) terminal = true;
                 didSomething = true;
-                //
-                // TODO wrap mutations in immer
-                state = mutation((action as any).payload, action)(state);
+                state = prepare(
+                    state,
+                    mutation((action as any).payload, action),
+                );
             });
 
         if (!didSomething && defaultMutation) {